During braking of a motor vehicle, each wheel is subjected to a large number of forces--for example the brake force, the dynamic wheel load (vertical forces on the axle during driving), rotatory forces, coupling forces, forces of inertra, etc.
The brake force as the most important of these forces depends in most brake systems on the brake pressure acting in the brake cylinder. The ratio of the brake force achievable in the tire contact area and the brake pressure in the brake cylinders that is, the brake coefficient or brake force development is therefore an informative quantity for checking or controlling the braking operation in these brake systems.